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SPRING 2003 VOLUME 5.1 C O O P E R A T I V E E X T E N S I O N U N I V E R S I T Y O F C A L I F O R N I A

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The Contaminated Issue INSIDE THIS ISSUE Dennis Pittenger Area Environmental Horticulturist, Central Coast & South Region 1. The Herbicide Con- taminated Compost Jim Downer Issue Environmental Advisor, Ventura County University of California Cooperative Extension An overview of contami- erbicide contaminated have Clopyralid Products and Use nated compost, the herbicide’s properties, suddenly come to the fore as another and recommendations Himportant environmental issue threat- Clopyralid is a pre- and post-emergent her- for the landscape ening California’s landscape and greenwaste bicide with activity against a narrow range industry are included. industries. Starting in 2001, articles of certain annual and perennial broadleaf began appearing in some of the state’s ma- . Products containing clopyralid have 2. Runoff jor newspapers which focused the public’s been on the U.S. market for more than 17 Laws and Their attention on the issue and raised its level of years and have been registered in California Enforcement in importance. It is borne out of problems that since 1997. California began in Washington state where herbicide- contaminated composts were found to be Clopyralid is a constituent of products sold Strict federal and state causing injury to . under several trade names registered for a water quality regula- tions are reshaping the variety of uses including cropland, rangeland, way agricultural Clopyralid was confirmed as the culprit by the turfgrass, roadside right-of-way and other operations are con- manufacturer, DowAgrosciences (formerly non- applications. Confront is a ducted and the known as DowElanco). Clopyralid residue has turfgrass herbicide that also contains direction of research since purportedly been found in finished com- programs in California tryclopyr and is registered for use in commer- and throughout the posts in California, but so far no dam- cial turfgrass applications and golf. Lontrel United States. age from tainted compost has been reported is an herbicide containing only clopyralid that in this state. The problem occurred in spite is also registered for commercial turfgrass. of warning language on many product labels Stinger is a product registered for use in ag- 3. Kikuyugrass to avoid composting clopyralid-treated plant ricultural , and Transline is used for in- Kikuyugrass cannot be material. This sparked a storm of controversy dustrial and right of way control. controlled with a and concern in the green industry and the Trupower is formulated for use by Trugreen/ single treatment or public over the safety of composted Chemlawn in their commercial applications procedure. A combi- greenwastes here in California. The follow- to turfgrass. Millenium is formulated by nation of cultural ing discussion is intended to provide infor- Scotts as a /herbicide granule for practices and herbi- cide applications are mation on clopyralid and the problems it use in golf and commercial turfgrass appli- most effective. causes in compost, the California situation, cations. Millenium Ultra, formulated by and suggest steps the landscape industry Riverdale Chemical Company, is a combina- can follow to minimize contamination of com- tion product (clopyralid, 2,4-D, and ) post. registered for use on ornamental turf sites Spring 2003 Volume 5.1 CC OO -- HH OO RR TT 2 such as golf courses and . No clopyralid products persist in the environment from a month to over a year. are available for use by homeowners in California. Its persistence is greatest in that are low in oxygen (compacted or water saturated most of the time) and low Clopyralid has excellent activity against certain difficult to in activity (cold, heavily graded or disturbed control leguminous weeds. In turfgrass it is particularly soils). It is degraded almost entirely by microbial action in effective in controlling clovers and dandelions. Use of soils or aquatic sediments, but not by sunlight or contact clopyralid enables applicators to attain control of certain with water. Microbial break down rates are highest in broadleaf weeds with fewer herbicide applications. How- warm, moist soils that are low in , and low- ever, a relatively limited amount of clopyralid is used in est in cold, dry, compacted or waterlogged soils. California on turfgrass due to its expense and narrow reg- istration of uses. The only identified clopyralid degradation product is car- bon dioxide. The inability of clopyralid to bind with soils Clopyralid Basics and Mode of Action and its persistence imply that it has the potential to con- taminate water resources and non-target plant species, Clopyralid is a plant growth regulator herbicide from the but no extensive offsite movement has been documented. picolinic acid group of compounds. In susceptible plants, Clopyralid is low in to aquatic animals and very low clopyralid disrupts -regulated processes, including in toxicity to most animals, but it can cause severe eye cell respiration and growth, causing uncontrolled and dis- damage including permanent loss of vision in humans. organized plant growth that leads to plant . Uptake of the herbicide is either through or , and it is Toxicity Problems and Compost Contamination both and xylem mobile. Translocation throughout the plant is rapid and the material accumulates in grow- Toxicity problems started in Spokane, Washington when ing points of the plant where it has its primary effect. symptoms were first noted on tomato plants. Clopyralid was found as a contaminant in greenwaste composts in- Clopyralid affects sensitive plants at a concentration as corporated in to the or applied around plants as . low as 10 parts per billion, — a very low concentration. The problem was noted at about the time that curbside Typical clopyralid toxicity symptoms include curved and recycling of green and the associated composting twisted stems and leaves, cupping and crinkling of leaves, programs began in that state. Since grass clippings are stem cracking, and hardened growth on stems and leaves. an important component in that state’s green wastes, they Complete browning and death can take a couple of weeks were soon identified as the source of the herbicide, and for seedlings or an entire season for susceptible peren- the origins of it were traced back to applications of Con- nial or woody plants. front to residential lawns.

Clopyralid is more selective (kills a more limited range of There are a number of desirable crop and ornamental plants) than some other auxin-disrupting like plant species among the families which clopyralid might , , or 2,4-D. Like these herbicides, affect including tomato, pepper, eggplant, potato, beans, clopyralid has little effect on grasses and other monocots. peas, sunflower, chrysanthemum, daisy, petunia, acacia, Also, clopyralid does little harm to members of the mus- honey locust and other leguminous plants. Age of the tard family (Brassicaceae) and several other groups of plant and rate of herbicide application will greatly impact broad-leaved plants. The basis of its selectivity is not well the degree of injury that might occur. Plants are most understood. Clopyralid is primarily effective against four tolerant to clopyralid applications when they are estab- plant families: Asteraceae (sunflower family); Solanaceae lished and when there is some woody tissue around the (nightshade/tomato family); Fabaceae (legumes/peas/ stem or trunk. Thus, it is believed that woody plants are clover family); and the Polygonaceae (buckwheat/knot- less likely to be damaged from the presence of clopyralid- weed family). contaminated compost in the landscape.

Clopyralid is water-soluble and does not bind strongly with The characteristics of clopyralid allow it to remain active soils or evaporate easily. The chemical breaks down com- and available for plant uptake for a long period, thereby paratively slowly in soil and persists in plant material, even reducing the amount of herbicide and number of applica- in non-susceptible and non-target species. Clopyralid may tions needed to achieve control of susceptible plants. Spring 2003 Volume 5.1 CC OO -- HH OO RR TT 3

Conversely, its characteristics cause a significant problem bedded on granules of 12-12-12 fertilizer. Sprayed plots when greenwaste from clopyralid-treated plants is received equivalent rates of fertilizer . Turf clip- composted. Clopyralid survives the composting process ping samples were collected in each mowing regime at 0, and very little of its residue is needed to cause toxic ef- 0.5, 1, 2, 3, 4, 5, 6, 7, 8, 9, and 10 weeks after clopyralid fects on non-target plants that come in contact with fin- treatment. Regardless of formulation, the mowing treat- ished composts used as soil amendments or . ment did not impact clopyralid concentration in clippings. By four and ten weeks after application, clopyralid con- Considerable study has been undertaken by the manu- centrations in clippings were 7% and 0.4% of their initial facturer to understand the persistence of clopyralid. concentrations in sprayed and granular formulation plots, Clopyralid persists to a variable degree in soil when ap- respectively. Concentrations still averaged 150 ppb in clip- plied to turfgrass or directly to soil as a pre-emergent treat- pings at ten weeks after application, which would be high ment, so it remains available for any plants present to enough in compost to cause injury to many plants. What take it up and translocate it. However, it was discovered is not known is what the final clopyralid concentration in that when grass clippings or other plant materials con- compost would be based on an initial concentration of taining clopyralid are composted, the herbicide becomes 150 ppb. A companion study is ongoing to measure the bound in the organic matter and it becomes more persis- clopyralid degradation during composting. tent, not less persistent after composting. For some time it was thought that the wrong microbes were in the com- What about California? post and that addition of new clopyralid degrading organ- isms found in soil would solve the problem. This was sub- In March 2003, the California Department of sequently tried and, unfortunately, it was shown that these Regulation (CDPR) initiated cancellation action against 15 organisms will not break down the herbicide when they clopyralid-containing herbicide products intended for use are added to finished composts. on residential lawns. New restrictions were announced by CDPR in April 2003 to further protect possible herbi- Other research showed that clippings collected between cide contamination of commercial composts. CDPR will 2 and 14 days after being sprayed with the herbicides restrict sales of clopyralid to and turf professionals, 2,4-D, triclopyr, clopyralid, or isoxaben caused unaccept- instruct those licensees to assure that green stays able injury to tomatoes, beans, and impatiens when ap- on site when the herbicide is used, and require dealers to plied directly as mulch around these plants. However, af- provide written notice of the restrictions when they sell ter composting these clippings all of the herbicides ex- some clopyralid products. CDPR is drafting regulations to cept clopyralid degraded to non-detectable levels during encourage those restrictions. 128 days or less of composting. In one study clopyralid was still detected after 365 days of composting. The agency expects its restrictions to affect about 15 cloryralid products used in parks, playing fields, and Based on this research, labels of herbicides containing cemeteries. Golf courses were exempted after CDPR de- clopyralid typically state that turfgrass clippings treated termined that grasscycling on site is a standard industry with the herbicide should not be used as a garden mulch, practice and that clopyralid product labels prohibit use on and treated clippings should not be used to make com- tees and greens. Clopyralid products labeled for farm, post during the season of herbicide application. rangeland, and forest use are not affected.

Recent research was conducted at the Washington State The new restrictions do not go as far as some in the com- University – Puyallup turfgrass research facility to address post industry would have liked. The industry lobbied for a the contaminated grass clipping problem. The objective ban on commercial uses. was to determine if mowing practices or formulation (sprayable or granular) could be used to limit the amount Compared to Spokane and perhaps other areas of the of clopyralid entering the compost stream over a 10 week Pacific Northwest, many of California’s urban areas pro- period. Clopyralid-treated turf was mowed weekly with duce greenwastes formulated from a variety of feed stocks clippings collected or mowed twice weekly with clippings with a higher proportion of woody materials to grass clip- returned. Clopyralid was applied to each mowing regime pings. Also, the Spokane area has a relatively high con- as a sprayable formulation or a granular formulation em- centration of residents who utilize commercial lawn care Spring 2003 Volume 5.1 CC OO -- HH OO RR TT 4 services, perhaps as much as twice the national average, so steps must be taken to keep such clippings from enter- and clopyralid is a popular herbicide used by them. There ing the greenwaste recycling stream. is a comparatively limited amount of clopyralid used in California landscapes and it is believed much of it, though Landscape managers should carefully consider whether not all of it is applied to turfgrass where the clippings are a clopyralid-containing herbicide is really needed to con- left to decay on the lawn (grasscycling), so they never en- trol the spectrum of weeds found in a given site. There ter the waste stream. In addition, Dow AgroSciences are other herbicides that effectively control many broad- clopyralid herbicides have label restrictions on using com- weeds but do not persist in turf clippings or other post containing grass clippings treated with the product. greenwaste. Also, turf that is maintained in good health and mowed at the correct height is less likely to be in- Despite all of this, trace clopyralid residues have purport- vaded by clover and other broadleaf weeds, which in turn edly been found in greenwaste composts in Los Angeles, reduces the need for herbicide applications. San Diego, and Sonoma Counties. Homeowners using professional lawn care services may not have been in- If a clopyralid-containing product is applied to turfgrass, formed that clopyralid was used, or may not have known take all necessary actions to ensure clopyralid-treated that restrictions apply, and unwittingly sent their grass clip- grass clippings are not allowed to be used as mulch or pings into the greenwaste stream. Fortunately, no seri- compost feed stock. Be certain to follow label instruc- ous damage has been reported on crop or ornamental tions and precautions and notify clients of the property plants receiving composted greenwastes in California. that turfgrass clippings are not to be composted or used as mulch. Using a mulching mower to return clippings to Clopyralid, and possibly other persistent herbicides, the lawn area is the best way to manage treated grass threaten the state’s greenwaste composting and recycling clippings. industry, the landscape industry, and state and local gov- ernment programs that promote and centralized Contaminated compost should not be used in vegetable composting as a method of dealing with greenwaste. Many , but it is probably safe to use it as a soil amend- in these industries and the public believe the existence of ment for lawns or woody landscape plants, as most of a class of herbicides that can damage the marketability these plants are not highly sensitive (although there may of compost products is contradictory to recycling, resource be exceptions). Compost should not be used as a sole conservation, and sustainability. growing medium, but should be mixed with soil at rates of up to 20% compost by volume. This will dilute clopyralid At this time, the potential or actual extent of contamina- residue to a level most plants can tolerate. Also, microor- tion in California greenwastes is unknown. There is need ganisms present in soil can break down clopyralid over for additional testing of greenwaste composts to get a time. It is recommended that landscape contractors ask clearer view of the threat. their compost supplier about possible clopyralid contami- nation. However, clopyralid contamination should not become a disaster for California because of CDPRs recent actions For additional information on clopyralid in compost, see and our compost feed stocks are diverse. It appears there the following web sources: is simply not enough clopyralid applied to turfgrass enter- 1. Washington State University: ing California’s greenwaste stream for it to be a wide- www.puyallup.wsu.edu/soilmgmt/Clopyralid.htm spread, serious problem in compost. www.css.wsu.edu/compost/compost.htm 2. Dow Agrosciences: Management Practices for Preventing Herbicide Contami- http://www.grrn.org/dow/DOW_Clopyralid_Compost_ nation of Composts 10-5-01.pdf http://www.wa.gov/agr/Dow_TolerantPlants.pdf There are multiple practices that can be followed to pre- vent herbicide contamination of greenwaste composts. 3. Technical background information on clopyralid: The greatest risk is from herbicide-treated grass clippings, http://tncweeds.ucdavis.edu/handbook.html (scroll down to Chapter 7 and click on “Clopyralid”) Spring 2003 Volume 5.1 CC OO -- HH OO RR TT 5

Bibliography Management Guideline Publication 3365-T. Available at http://www.ipm.ucdavis.edu/PMG/crops- California Landscape Contractors’ Assoc. 2003. Califor- .html. nia announces restrictions to protect compost. Sacra- Green, E. 2002. Recycling of is threatened. mento: The Cutting Edge Newsletter. Los Angeles: Los Angeles Times newspaper article, Feb- Brank, G. 2002. DPR acts to protect compost from herbi- ruary 19, 2002. cide. Sacramento: California Department of Pesticide Green, E. 2001. Potent toxin taints efforts at composting. Regulation. News release dated March 27, 2002. Los Angeles: Los Angeles Times newspaper article, De- Dow Agrosciences Representatives. 2002. Personal com- cember 27, 2001. munications. Lauer, G. 2002. Herbicide shows up in compost. Santa Dow Agrosciences. 2001. Clopyralid and compost. - Rosa, CA: Press Democrat newspaper article, April 5, napolis: Dow Agrosciences. 2002. Elmore, C. L., D. Cudney, V. Gibeault, and C. Wilen. 2000. Lauer, G. 2002. Chemical kills broadleaf plants, threat Susceptibility of weeds to herbicides. University of Cali- to greenwaste recycling. Santa Rosa, CA: Press Demo- fornia Division of Agriculture and Natural Resources, crat newspaper article, February 21, 2002. Statewide Integrated Pest Management Project. U.C. Miltner, E., A. Bary, and C. Cogger. 2002. Clipping man- Pest Management Guideline Publication 3365-T. Avail- agement and herbicide residue in home lawns. Proceed- able at http://www.ipm.ucdavis.edu/PMG/crops- ings California Weed Science Society 2002 Annual Con- agriculture.html. ference. Elmore, C. L., D. Cudney, V. Gibeault, and C. Wilen. 2000. Rohlfes, L. 2002. Personal communication. Turfgrass special weed problems. University of Califor- Tu, M., C. Hurd, and J. M. Randall. 2001. nia Division of Agriculture and Natural Resources, State- methods handbook: tools and techniques for use in natu- wide Integrated Pest Management Project. U.C. Pest ral areas. Davis, CA: Nature Conservancy web site at http://tncweeds.ucdavis.edu/handbook.html.

Runoff Water Quality Laws and Their Enforcement in California

Donald Merhaut Extension Specialist for Ornamental and Crops Dept. of and Plant Science, University of California, Riverside

Water Quality Regulations are reshaping the way agri- to the original WPCA. By the 1960s, the government real- cultural operations are conducted in the United States ized that only focusing on point sources of was and throughout the world. not enough since surface and groundwater sources were still impaired. Therefore, in 1972, the WPCA was again Federal Water Quality Regulations amended with §303(d), which pointed toward regulations for water quality standards from both non-point in addi- Water quality regulations in the United States began in tion to point source polluters. This amendment also re- 1948 with the induction of the Federal sulted in the renaming of the WPCA to the Clean Water Control Act (WPCA) of 1948. This policy, created and Act (CWA). This act now has two major programs: funded by the federal government, delegated responsibil- ity of law development and implementation to each state (1) The Total Maximum Daily Loads (TMDLs), a set of (Houck, 1999). Since its creation, many amendments have narrative recommendations that define how much of a been added (Table 1) which has resulted in major changes specific a water body can receive on a daily ba- sis without compromising water quality. Spring 2003 Volume 5.1 CC OO -- HH OO RR TT 6

(2) The National Pollutant Discharge Elimination System In order to oversee these programs the EPA has divided (NPDES), which requires point-source polluters to mitigate the continental U.S. and associated territories into ten effluent to meet specific water quality standards. Point- regions (Fig. 1 – http://www.epa.gov/ceppo/sta-loc.htm). source pollution is defined as ‘discernable, confined, and Each region has an office, which is responsible for assist- discrete conveyance’. The industries under this definition ing states in the implementation and enforcement of wa- included factories, water treatment plants, and urban ter quality policies. storm conveyance systems. However, the difference be- tween point and non-point polluters is becoming less de- California Water Quality Regulations fined as developments such as golf courses, nurseries, and commercial urban landscapes become labeled as Like all other states in the U.S., California was aware of point source instead of non-point source polluters. the water pollution problems in their region. Therefore, The state developed its own water quality regulations. In 1969, California enacted the Porter-Cologne Water Qual- Under the Clean Water Act §303(d), states are to: ity Control Act (PCWQCA). Based on the PCWQCA, waste discharge permits (WDR), which meet the requirements (1) Identify the water resources that are polluted, for the federally regulated NPDES, are issued to anyone releasing waste into waterways. However unlike the fed- (2) Establish the TMDLs that will restore water quality, eral regulations, these permits are not only issued to point and source polluters, but also those that would be considered under federal regulations to be non-point source pollut- (3) Allocate pollutant loads to discharge sources via state ers. water programs and discharge permits.

Table 1. History of federal and California clean water quality regulations as they pertain to agricultural operations.

Date of Public Program creation Law #

1948 Water Pollution Control Act (WPCA) – federally funded. State regulated program 80-845 to clean water polluted from point sources. 1965 Amendment to WPCA - provided federally approved water quality standards for 89-234 interstate waters. Name changed to Water Quality Act of 1965. 1969 California Porter-Cologne Water Quality Act – state policy to regulate waste NA discharge. No distinction made between point and non-point source polluters. Fulfilled the federal requirements that would be established with amendment §303(d) in 1972. 1972 Amendment §303(d) of Water Pollution Control Act – Regulations introduced 92-500 with the Total Maximum Daily Loads (TMDLs) guidelines. Name eventually changed to the Clean Water Act. 1977 Amendment added – provided for the development of “Best Management 92-500 Practices” programs. Name changed to the Clean Water Act of 1977. 1987 Amendment §304(l) and §319 – development of numerical rather than narrative 95-217 water quality criteria. §319 addresses non-point source polluters Name changed to the Water Quality Act of 1987. However, most still refer to the act as the Clean Water Act.

Spring 2003 Volume 5.1 CC OO -- HH OO RR TT 7

Because of the large geographical size and the diverse ists threatened to sue several municipalities in this area industries in California (Fig. 2), pollution sources (Fig. 3) in the late 1980s. The pending lawsuits resulted in a se- differ throughout the state. For instance, many nurseries ries of policy implementations which initiated a chain re- and dairies operate in southern California; therefore, ni- action of similar suits in the central and northern regions trates and phosphates are major pollutant in this area. In of the state. northern California, excess deposition of sediments into waterways is a primary concern due to erosion caused by Even though all RWQCBs are following the PCWQCA, the the logging industry. Major differences in climate, espe- regulations that have been developed differ from region cially rainfall also complicate water quality issues. To con- to region. In San Diego (Region 9), runoff is limited to only front this problem, the State Water Resources Control storm water, excluding the runoff from the first storm event, Board (SWRCB) has divided the state into nine regions which must be captured. Because of this ‘zero runoff’ (Fig. 4), with each region housing its own Regional Water policy, TMDLs and other similar regulations pertaining to Quality Control Board (RWQCB). Each region, under the runoff water have no applicability in the San Diego Basin. direction of the SWRCB is to develop pollutant discharge In the Santa Ana Basin (Region 8), runoff is allowed, but a standards based on the level and type (pollutant) of im- WDR must be issued. Many physical and chemical re- pairments they encounter in their area. From the policies strictions must be followed according to the Santa Ana developed, WDR permits are issued to individuals. Basin Plan (Table 2). One of the most restrictive is the electrical conductivity (EC), which must not exceed 2.0 dS/ Current Regional Regulations M. This is challenging for most nurseries in this area, since most water is derived from the Colorado River, The San Diego Water Basin (Region 9) was the first area which usually has an EC of 1.5 dS/M. In the North Coast to be affected by policy implementations. Environmental- (Region 1), WDR are required, but only during the con-

Figure 1. Map of the United States showing the division of the nine water districts as established by the EPA. Map is courtesy of the USEPA (http:// Figure 2. Agricultural commodities of California www.epa.gov/ceppo/sta-loc.htm). and their geographical distribution. Spring 2003 Volume 5.1 CC OO -- HH OO RR TT 8

Figure 3. Map of the California showing the different types of pollu- tion present.

struction of nursery facilities. However, no WDR is required for normal nursery opera- tions. Based on the history of water quality regulations in California, it is likely that stricter regulations will fall upon the nursery industries throughout the state. Cur- rently, grants have been funded to the University of California Cooperative Exten- sion and growers associated with the nursery and floriculture industries in San Diego and Los Angeles counties to study and develop Best Man- agement Practices (BMPs) to meet the water quality regu- lations set forth by the state and federal governments. In San Diego (RWQCB 9), a $300,000 grant was funded through Proposition 13 monies to implement BMP pro- grams for nursery growers. In the fall of 2003, a similar grant of $3,000,000 will be funded for the development of BMP programs in Ventura County (Region 4).

Literature Cited

California Regional Water Quality Control Board, Santa Ana Region. 1995. Water quality control plan Santa Ana River Basin (8). Houck, O.A. 1999. The Clean Water Act TMDL Program: Law, Policy, and Implementation. Environmental Law Institute, Washington, D.C. Figure 4. Map of California, USA, showing the Porter-Cologne Water Quality Control Act.. 2000. Califor- boundaries of the state’s nine Regional Water nia Office of Legislative and Public Affairs. Quality Control Boards (RWQCB). Water quality Ruffolo, J. 1999. TMDLs: The revolution in water quality regulations are overseen by the State Water Qual- regulation. California Research Bureau, Sacramento, CA. ity Resources Control Board (SWQRCB) which United States Environmental Protection Agency. 1994. delegates the responsibility for the development Water Quality Standards Handbook: Second Edition. Wa- and implementation of regional basin plans to the ter Quality Standards Branch, Office of Science and Tech- nine RWQCB. Map Courtesy of State of California, nology, Washington D.C. 2000, California Environmental Protection Agency, State Water Resources Control Board. http:www.swrcb.ca.gov/regions.html. Spring 2003 Volume 5.1 CC OO -- HH OO RR TT 9

Table 2. Chemical parameters that have been listed by the EPA and adopted by the Water Quality Santa Ana River Basin (Region 8). Only those chemicals that may be of concern for nursery operations have been listed. Data from the ‘Water Quality Control Plan, Santa Ana River Basin (8)’, 1995.

Chemical Water Body of Environmental/Human Impact Chemical Limits in Regulation Wastewater1

Chlorine (Cl) Ocean, Aquatic life -Chlorine and its reactants NA Inland surface water, can be toxic to aquatic life. Groundwater Hydrogen Ion Ocean, Aquatic life - that change pH Ocean -pH 7.0-8.5. Concentration (pH) Inland surface water, can harm aquatic life. Inland Waters-pH 6.5-8.5 Groundwater Structural - Extreme water pH can Groundwater - pH 6.0-9.0 deteriorate pipes and concrete. - Inland surface waters Waterfowl - Reduced water surface NA detergents, tension can drown waterfowl. emulsifiers and Aquatic life – Surfactants may affect wetting agents some aquatic life. Aesthetics - Foaming is a physical and aesthetic problem. Toxic Substances Ocean, All life forms - Toxic substances cannot NA Inland surface water be discharged at quantities that bioaccumulate to toxic levels to humans. Toxic pollutants in water, sediments or biota should not affect beneficial uses. Boron (B) Inland surface water, Higher plants - High levels (>0.75 mg/L) NA Groundwater are toxic to many plants. Human health - Boron is toxic when concentrations exceed 20-30 mg/L Total Dissolved Inland surface water, Plant life - Dissolved mineral content NA Solids (TDS) Groundwater should be less than 700 mg/L when used for agriculture.

Nitrate (NO3) Inland surface water, Human health - Infants develop blue NA Groundwater baby syndrome (methemoglobinemia). Drinking water standard cannot exceed 10 mg /L or 45 mg nitrate/L. Iron (Fe) Groundwater Human and animal health - High 0.3 mg/L concentration of metals are toxic. Manganese (Mn) Groundwater Human and animal health - High 0.05 mg/L concentration of metals are toxic. 1 NA indicates that no specific chemical concentrations were available. Spring 2003 Volume 5.1 CC OO -- HH OO RR TT 10

Kikuyugrass

David Cudney1, Clyde Elmore2, and Victor Gibeault3 1Weed Specialist, Emeritus, Dept. of Botany and Plant Sciences, University of California, Riverside; 2Weed Scientist, Emeritus, Vegetable Crops/Weed Science, University of California, Davis; and 3Extension Environmental Horticulturist, Dept. of Botany and Plant Sciences, University of California, Riverside

Kikuyugrass (Pennisetum clandestinum) is an extremely or stem sections before moving it from infested areas. aggressive perennial weed of turfgrass, ornamental Kikuyugrass has also been spread in contaminated soil, plantings, , and noncrop areas in California. Na- sod, and planting stock. Make sure that any incoming tive to Africa, kikuyugrass is well adapted to warm, tem- materials are free of contamination. Maintain turfgrass perate climates such as those of the coast and inland and ornamental areas to assure they are at maximum vigor valleys of southern and central California. Kikuyugrass so that these plantings are as competitive as possible to was originally imported to California around 1918 as a help slow the invasion of this weed. Dense turfgrass and ground cover to reduce erosion on banks. With its ornamental plantings shade the soil surface, making the rapid stolon growth and thatch formation, it quickly moved establishment of kikuyugrass sprigs and seedlings more from these sites and became a serious weed pest. In the difficult. Vigorous, tall fescue varieties have been effec- past kikuyugrass was often confused with St. tive at reducing kikuyugrass invasion when used in the Augustinegrass and may have been mistakenly propagated turfgrass. Regularly inspect orchards and noncrop areas and planted in its place. for the presence of kikuyugrass and other invading weed species. Remove the invading species by hand or spot- Impact treat them with an herbicide to prevent their spread.

Kikuyugrass is a major weed problem in turfgrass and or- Control namental areas but can also be found in coastal and in- land valley orchards of southern and central California. It Kikuyugrass cannot be controlled with a single treatment causes physical, aesthetic, and competition problems. In or procedure in turfgrass. A vigorously growing turf coupled turfgrass it forms thick mats that crowd out desirable spe- with early grubbing (removal of the entire plant, roots and cies. The thick mat makes golf and other athletic uses all) of solitary infestations has been successful when prac- difficult and in some cases dangerous. The light green ticed diligently. Spot-spraying isolated plants with color and coarse texture of kikuyugrass is not aestheti- can be helpful but will also kill the turfgrass, cally desirable compared to other turf species. In golf leaving open areas in which kikuyugrass can easily rees- courses it often invades greens and requires hand re- tablish itself. Overseed the open spots with the desired moval. In ornamental areas it invades ground covers and grass species to establish a vigorous turfgrass. flower beds, often completely choking them out. Kikuyugrass can invade low-growing shrubs, blocking out When they are applied in March, preemergent herbicides light and reducing vigor. In orchards it can compete with have been successful in limiting germination of trees for nutrients, interfere with irrigation by blocking kikuyugrass in spring and early summer. sprinklers and emitters or drainage , and overgrow , , benefin, and prodiamine are fences. available for use around the home. Because this weed spreads primarily by regrowth from stem sections, mul- Management tiple applications of a postemergent herbicide are required to control established infestations. In cool-season The best way to control kikuyugrass is to prevent its spread turfgrass (tall fescue, perennial ryegrass, and Kentucky into new areas. Kikuyugrass can be spread both from bluegrass) about three to four applications per year are and from stem sections and seems to be most com- necessary. Best control has been obtained from sequen- monly spread by mowing, cultivation, and renovation equip- tial applications of a combination of triclopyr and MSMA ment. Clean equipment to remove any kikuyugrass seed applied 4 to 6 weeks apart. Both are available for use Spring 2003 Volume 5.1 CC OO -- HH OO RR TT 11 around the home. Sequential applications of either MSMA or triclopyr alone will reduce kikuyugrass vigor and growth, but are not as effective as the combination. Victor A. Gibeault Extension Environmental Horticulturist In bermudagrass turf, either or MSMA can be Department of Botany and Plant Sciences used alone or in combination to reduce a kikuyugrass in- University of California, Riverside vasion. Sequential applications will be necessary. Quinclorac is only available to commercial applicators.

References Donald J. Merhaut Extension Ornamental & Floriculture Crops Specialist Cudney, D. W. et al. 1994. Herbicide program can control Department of Botany & Plant Science kikuyugrass in cool-season turf. Calif. Agric. 48(2):24- University of California, Riverside 28. Cudney, D. W. et al. 1993. Kikuyugrass (Pennisetum clandestinum) management in turf. Weed Tech. 7(1):180-184. Dennis R. Pittenger Cudney, D. W. et al. 1982. Chemical and cultural control Area Environmental Horticulturist of kikuyugrass in turf. Calif. Agric. 36(1):4-5. Central and South Region and Los Angeles County Elmore, C. L., V. A. Gibeault, and D. W. Cudney. 1997. University of California Invasion resistance of tall fescue (Festuca arundinaceae) and perennial ryegrass ( perenne) Co-Hort is published 3 times per year (Spring, Summer, Fall) to kikuyugrass (Pennisetum clandestinum). Weed Tech. and distributed to U.C. Farm Advisors, Specialists, and 11(1):24-29. Department Faculty associated with environmental horticulture. It summarizes current research and information on issues related to urban landscapes, turfgrass, and ornamental/floriculture crop production in an effort to support research and educational programs meeting the environmental horticulture industry’s Adapted from: Pest Notes, Publication 7458, Revised April needs in California. This publication is written and edited by 2003. Produced by IPM Education and Publications, Uni- Victor A. Gibeault, Donald J. Merhaut, and Dennis R. Pittenger, versity of California Statewide IPM Program. and prepared by Susana B. Aparicio, Administrative Assistant. Please address any correspondence concerning this publication to the editors.

Co-Hort is issued in furtherance of Cooperative Extension work, Acts of May 8 and June 30, 1914, in cooperation with the U.S. Department of Agriculture, W. R. Gomes, Director of Coopera- tive Extension, University of California.

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